IPA: /sɜːr.kjʊˈleɪ.ʃən/
KK: /sɜrˈkjʊˌleɪʃən/
The process of moving something around or spreading it widely, such as information, printed materials, or fluids in a system.
The circulation of the magazine has increased significantly this year.
Circulation is formed from "circum-" (meaning around) and "-culare" (from Latin "calare", meaning to call or summon). The word describes the process of something moving around in a system, such as blood circulating in the body.
Think of something moving 'around' ('circum-') and being 'called' or 'summoned' ('calare') in a system — that's how circulation works.